Cash Is A Different Animal
The blinds are constant in cash, so there are no ‘game phases’ as there are in SNGs. The stacks tend to be much deeper stacks in cash than SNGs. This statement is a generalization; you can fall to a 10 BB (big blind) stack in cash without rebuying, and some SNGs start with 100 BB stacks. In general, though, cash is played with stacks of 50-100 BB or deeper, whereas most of the important decisions in SNGs take place with stacks of 20 BB or fewer.
Chips do not change value in cash-game play. In SNG play, it’s important to understand that you are playing for equity rather than chips. Suppose you are one of two big stacks on the bubble. You would not call an all-in from the other big stack unless you had a very large edge, because doing so risks your entire equity when you are almost guaranteed a money finish. Cash play is different, however – chips and money are identical. You are correct to take any edge.
(In practice, you might decline to call off your entire stack in cash with a very small edge, in order to lower variance. In theory, though, you’re correct to seize even the smallest edge.)